Vibrations are not transmitted to the ground which prevents micro cracks to appear in the road around the gray cast iron manhole.

Vibration damping ratio is high thus it is not necessary to install flexible inserts that are indispensable for ductile iron.

Flake graphite in gray cast iron prevents corrosion from penetrating deeper making it resistant to pitting corrosion.
There’s no need for painting.

There’s no need to apply additional elements (latches) to prevent the covers from lifting.
Thanks to stable and simple construction, service life of gray cast iron products is longer.

Thanks to stable and simple construction, service life of gray cast iron products is longer.

Thanks to the high vibration damping ratio noise level is low.

A higher thermal conductivity ratio results in better and more even heat dissipation to the surface around the manhole, which prevents it from cracking and deformation.

Thanks to the highest durability, gray cast iron is recommended for roads with heavy traffic.

Product strength classes A, B, C, D, E, F divide manholes and inlets in terms of the pressure they may be subjected to after installation on the road. Due to the varied road conditions in which products in class D400 are used, KZO S.A. introduced their additional division into 2 groups depending on the level of traffic intensity on the road on which they will be used:

RI – Intense traffic
RŚ – Medium traffic

The above markings can be found in the catalogue and catalogue cards in tables with class D400 products. The selection of the appropriate product class is at the discretion of the design units and the client, and depends on the specificity of the road. In case of doubts as to the appropriate class of the product, a higher class should be used. Similarly, in case of doubts as to the determination of the intensity of traffic on the roadways where the tops will be installed, one should select manholes/inlets intended for intensive traffic.